At the time of forming a color filter used for a liquid crystal display apparatus, in general, a method of forming a light shielding part on a transparent substrate for forming a color filter, and forming a colored layer in the opening part thereof, or the like is used. As such a light shielding part, conventionally, a metal thin film with a metal such as a chromium vacuum deposited and processed by etching has been used. Recently, however, development of a resin-made light shielding part formed by coating a resin with a black pigment, or the like dispersed and patterning by the photolithography method, or the like has been promoted so as to realize its practical use. According to such a resin-made light shielding part, as compared with a light shielding part comprising a metal thin film, the process of the vacuum deposition or the like can be eliminated so as to be used for a large area color filter, and thus it is advantageous.
However, as compared with the light shielding part comprising a metal thin film of such as a chromium, for obtaining a sufficient optical density, the film thickness should be large. Therefore, the film thickness of the colored layer formed to cover a part of the resin-made matrix for the purpose of preventing the void, or the like is made larger. As a result, the difference in the film thickness between the region with the light shielding part and the colored layer laminated, and the region with only the colored layer formed becomes larger.
In particular, in the case where the colored layers of such as red (R), green (G), blue (B) are formed by a plurality of times on a transparent substrate with the light shielding part formed, the difference in the film thickness between the region with the light shielding part and the colored layer laminated, and the region with only the colored layer formed becomes larger. The method for forming the colored layer of such a color filter will be explained with reference to, for example, FIGS. 4A to 4E. First, the colored layer 3R of a first color is formed on the opening part of the transparent substrate 1 with the light shielding part 2 formed so as to cover a part of the light shielding part 2 by the photolithography method, or the like (FIG. 4A). Subsequently, by coating a colored layer forming composition 4B for forming the colored layer of a second color onto the transparent substrate 1 with the colored layer 3R formed (FIG. 4B), and curing only the purposed region, a colored layer 3B is formed (FIG. 4C). Here, at the time of coating the above-mentioned colored layer forming composition 4B, the colored layer 3R is formed on the transparent substrate 1 so that the film thickness of the colored layer forming composition 4B coated thereon becomes larger in the vicinity of the region with the colored layer 3R formed. Therefore, the film thickness on the colored layer 3R side of the colored layer 3B to be formed by curing the colored layer forming composition 4B becomes higher than the film thickness of the colored layer 3R. In the same manner, in the case of applying a colored layer forming composition 4G to be formed for the third color (FIG. 4D), since the colored layers 3R, and 3G are already formed on the both sides of the region for forming the colored layer, the film thickness of the colored layer forming composition 4G becomes higher in the vicinity thereof so that at the time of providing the colored layer 3G by curing, or the like, as compared with the colored layers 3R and 3B, the film thickness in the region laminated with the light shielding part 2 becomes higher (FIG. 4E).
In the case where the color filter has a difference in a film thickness between the region with the light shielding part and the colored layer laminated and the region with only the colored layer formed accordingly, the problems such as a disturbance of the alignment of the liquid crystal in the liquid crystal layer formed on the color filter so as to generate the light leakage, or breakage of the ITO film formed on the color filter have been generated. Furthermore, the problem such as causing unevenness of the gap at the time of disposing the color filter and the counter substrate to face to each other has been involved.
Moreover, in the case of a color filter having a stripe-shaped colored layer, for example, as shown in FIG. 5A, the colored layer 3 is formed in a stripe form on the transparent substrate with the light shielding part 2 formed. Here, the light shielding part 2 is formed orthogonally with the colored layer 3 in the a direction. For example, as shown in the cross sectional view in the b direction (FIG. 5B) of FIG. 5A, in the portion with the light shielding part 2 orthogonal to the colored layer 3, the light shielding part 2 is totally covered with the colored layer 3. At the time, as mentioned above, in the case where the film thickness of the resin-made light shielding part 2 is large, the difference in the film thickness between the region with the light shielding part 2 and the colored layer 3 laminated, and the region with only the colored layer 3 formed becomes larger. Moreover, since the difference in the film thickness continues like a line in the a direction, it may become a cause of further disturbing the liquid crystal alignment or a cause of generating the breakage of the ITO film.